:口，is used to ask about the number of people in the family “几口人”is used to ask about the number of people in the family only. When one wants to ask about the number of people in an institution or a community, he should use the measure word “个”.
“几口人”只用于询问家庭的人口。其他场合询问人数时，量词要用“个”。
For Example:
“你家有几口人？” How many people are there in your family?
: 
:口，is used to ask about the number of people in the family “几口人”is used to ask about the number of people in the family only. When one wants to ask about the number of people in an institution or a community, he should use the measure word “个”.
“几口人”只用于询问家庭的人口。其他场合询问人数时，量词要用“个”。
For Example:
“你家有几口人？” How many people are there in your family?